’ 
120 DESCRIPTIONS OF MINERALS. 
Obs. Ii occurs with other silver ores at Freiberg, Schnee- 
berg, and Johanngeorgenstadt, in Saxony; also in Bohe- 
mia, and Hungary. It is an abundant ore in Chili, Peru, 
and Mexico, and also in Nevada, and at the Comstock Lode, 
and at Ophir, and Mexican mines, in the Reese River and 
Humboldt, and other regions ; in Colorado and Idaho. It is 
sometimes called black silver. 
Polybasite is near stephanite in color, specific gravity, and composi- _ 
tion, but contains some arsenic and copper, with 64 to 72°2 per cent. of 
silver. The crystals are trimetric, aud usually in tabular hexagonal 
prisms, without distinct cleavage. G.—6,214. From Freiberg, Przi- 
bram ; Mexico and Chili; the Reese mines in Nevada, and Idaho. 
Miargyrite is an antimonial silver sulphide, containing but 36°5 per 
cent. of silver, and having a dark cherry-red streak, though iron-black 
in color. B.B. on charcoal gives off fumes of antimony and an odor 
of sulphur ; and in the oxidating flame, a globule is left which finally 
yields a button of pure silver. 
Brongniardite occurs in regular octahedrons and massive, grayish- 
black in color, and contains about 25 per cent. of silver, with lead, an- 
timony, and sulphur G.—5-95. From Mexico. 
Polyargyrite algo is isometric, having cubic cleavage, and is from 
Wolfach in Baden. It. is near polybasite in composition=12Ag, S+ 
Sb, 8s. 
Freieslebenite is a monoclinic antimonial silver-and-lead sulphide, of 
a light steel-gray color, with G.—6-6°4. Contains 22 to 24 per cent. 
of silver. From Saxony, Transylvania, and Spain. 
Pyrostilpnite is another monoclinic silver ore ; its delicate crystals 
are grouped like stilbite and have a fire-red color. Contains 62°3 per 
cent. of silver. From Freiberg, Andreasberg, and Przibram. 
Cerargyrite.—Horn Silver. Silver Chloride. 
Isometric. In cubes, with no distinct cleavage. Also 
massive, and rarely columnar; often incrusting. Color 
eray, passing into green and blue; lookssomewhat hke horn 
or wax, and cuts hike it. Lustre resinous, passing into ada- 
mantine. Streak shining. ‘Translucent to nearly opaque. 
Composition. Ag Cl=Chlorine 24°7, silver 75°3. Fuses 
in the flame of a candle, and emits acrid fumes. B.B. af- 
fords silver easily on charcoal. The surface of a plate of 
iron rubbed with it is silvered. 
Obs. A very common ore and extensively worked in the 
mines of South America and Mexico, where it occurs with 
native silver; and also abundant in Nevada about Austin, 
Lander Co. ; in Idaho at Poor Man’s Lode ; occurs also in 
Comstock Lode; and in Arizona; also at the mines of Sax- 
ony, Siberia, Norway, the Hartz, and Cornwall. 

